Apparatus for casting molten metal

ABSTRACT

Molten metal is forced upwardly by bottom pressure casting through an ingate and into the casting cavity of a mold having a dam to retain the metal in the cavity after the ingate has been drained. The mold is preferably formed from separable graphite cope and drag sections and may include an outer cast iron chill ring to impart the desired outer contour to the casting with accuracy. A plurality of such molds may be stacked and filled in one pouring operation.

nited States Patent Zickefoose [451 Apr. 18, 1972 [54] APPARATUS FORCAS'HNG MOLTEN 953,999 4/1910 Levering 164/371 METAL 1,797,041 3/1931Becker... 164/309 2,195,960 4 1940 Morris... ..164 336 [72] lnVelltOl'ZElllS J. ZlckefOSe, Elmhurst, 2,852,822 9l958 Strom l64/36 x Assignee;Amsted Industries Incorporated Chicago, Gl'oteke m. 3,532,154 10/1970Balevski et a1 ..164/337 X [22] Filed: Jan. 29, 1969 FOREIGN PATENTS ORAPPLICATIONS [2l] Appl. No.: 794,974 13,593 7/1909 l Great Britain164/306 477,384 7/1915 France [52] U.s. c1 .164/3119, 164/119, 164/129290936 5/1928 Great Bma --164/306 [51] Int. Cl. 132211 17/06, B22d 27/14[5s] Field ofsearch ..164/1 19, 77, 62, 129, 133, Pf'ffmfy Emmfef-lSpencefovefholsef 164/143, 4, 306, 309, 371, 372, 373, 63, 65AssistantExaminer-1l E. Roethel Attorney-Walter L. Schlegel, Jr. andRussell W. Pyle [56] References Cited [57] ABSTRACT UNITED STATESPATENTS Molten metal is forced upwardly'by bottom pressure casting1,013,548 1/1912 Grey..- ..164/1 19 through an ingate and into thecasting cavity ofa mold having 2,210,544 8/ 1940 G21110W2y- -1641 19 X adam to retain the metal in the cavity after the ingate has 3,506,061 4/1970 Clemm 164/ 129 X been drained. The mold is preferably formed fromseparable 1,579,743 4/ 1926 WarlOW, Jr- 164/129 graphite cope and dragsections and may include an outer cast 1,358,435 1 1/ 1920 1:1'21I11164/129 X iron chill ring to impart the desired outer contour to thecast- 3,532,154 l0/ 1970 Ba1eVSkl--- --164119 ing with accuracy. Aplurality of such molds may be stacked 1,1 Grey 1 8 and in one pouringoperation. 2,448,903 9/1948 Millen... ....164/306 UX 407,732 7/1889.lowitt 164/371 X 4 Claims, 2 Drawing Figures "11s "t 6 ini l 5, 11 7oil@ 9.1.? f j y 54 111i i l, "z 4s 'ug 4o 26 22 2| e5 M'""f-Y4 A 20 a 2e,mwfrr PATENTEDAPR 1a ma FIG. l

INVENTOR. EL LIS J. ZICGEFOOSE APPARATUS FOR CASTING MOLTEN METALBACKGROUND OF THE INVENTION l Field of the Invention This inventionrelates to a method and apparatus for casting molten metal and moreparticularly to a bottom pressure casting operation wherein molten metalis forced upward by the application of superatmospheric pneumaticpressure into a mold where the metal solidifies or partially solidifies.

2. Description of the Prior Art After the casting cavity of the mold isfilled in a bottom pressure casting operation, means must be employed toretain the metal in the mold until the desired degree of solidificationhas occurred, in order to prevent the metal from returning to the ladle.The various methods that have been employed for this purpose haveincluded constant pressure systems and mechanical valve devices.

The constant pressure system employs a suitable valve arrangement inconjunction with the pneumatic pressure source to maintain the pressureon the molten metal constant at a level required to retain the metal inthe mold. One type of mechanical arrangement includes a refractorystopper in the ingate of the mold, which is closed upon completion'ofthe pouring operation. Another mechanical device comprises a horizontalslide having an open position during the pouring operation and movableto a closed position after the casting cavity has been filled.

While the above mentioned methods have been found to be effective andcommercially successful, they are not readily adaptable to theproduction of certain shapes, such as those having a central void. Theuse of a stopper or slide may necessarily cause entrapment of the metalin the central portion of the casting cavity as well as in its outerperiphery, requiring the later removal of the central solidified metalto produce a finished product. Since the entrapment of excess metal isdetrimental to a high yield, it is highly desirable, if possible, toinitially cast the article in its substantially finished or final shape.

Accordingly, an object of this invention is to provide a method andapparatus for casting articles by bottom pressure casting that does notemploy mechanical means or pneumatic pressure means to retain the moltenmetal in the mold upon completion ofthe pouring operation.

Another object of this invention is the provision of a novel moldstructure which retains substantially only that molten metal needed toform the desired casting.

SUMMARY OF THE INVENTION The above objects are accomplished by means ofa weir or dam in the casting cavity, which retains metal therein butallows excess metal to return to the ladle upon relieving pressure tothe tank. A novel mold construction is also employed, utilizinginterchangeable intermediate mold sections to form a plurality of moldcavities.

BRIEF DESCRIPTION OF THE DRAWING FIG. l is a vertical sectional view ofa bottom pressure casting apparatus that incorporates features of thepresently described invention; and

FIG. 2 is a plan view ofthe cast iron contour ring used in the moldshown in FIG. l.

DESCRIPTION OF THE PREFERRED EMBODIMENT With more particular referenceto the drawing, the apparatus for bottom pressure casting shown in FIG.l comprises a ladle, generally indicated at 10, having an innerrefractory lining 12 and an outer metallic shell 14, said ladle beingdisposed within a pressure tank 16. A cover 18 having suitableinsulation 20 on the inner side thereof is releasably clamped on thepressure tank 16 by means of a suitable clamping device, generallyindicated at 22, and is sealed to the tank by an annular resilient seal21 therebetween. As shown, the

clamping device 22 may include a lever 24 pivotally suspended from theedges of the cover I8. A hydraulic or pneumatic ram 26 may be mountedupon the tank supporting framework 28 to engage an arm 23 of the lever24 in a downward direction. A roller 25 may be mounted on the lever 24to be engageable with a flat vertical to the tank 16.

A refractory pouring tube 30 is disposed centrally within the ladle l0with its lower end 31 proximate the bottom of the ladle and its upperend 33 extending through and above the cover 18 and secured to anadapter 32 sealed to the cover. The tank 16 is thus substantiallysealed, such that application of superatmospheric pressure thereto froma suitable source, such as that indicated at 34, connected to the tankwill cause the molten metal 36 to rise upward in the pouring tube 30 tofill the mold 40.

The upper portion of the adapter 32 is flared outward at 38 to receive afemale member 42 of the mold assembly, generally indicated at 40. Themold assembly 40 is composed of a chill material, such as graphite, andcomprises an upper or cope section 44 and a lower or drag section 46,which in turn communicates with an ingate 48 formed centrally therein.The mating surfaces of the cope and drag sections are machined or formedto together define a casting cavity such as 50 therebetween, with acommon central passageway 52 in cornmunication with the ingate 48 forthe admission of molten metal from the ladle 10. The passageway 52 inthe cope section 44 extends upward and is open to the atmosphere.

As shown in FIG. ll, the mold assembly 40 may also comprise one or moreintermediate and interchangeable mold sections 54 between the cope 44and drag 46 sections, the purpose of which is to form additional castingcavities. It may be seen that the underside of each intermediate moldsection 54 is adapted to serve as the cope section for the mating moldsection located therebelow, while the upper side is adapted to serve asa drag section for the mating section thereabove, thereby defining aseries of casting cavities in a vertically spaced relationship. Theintermediate sections 54 and the cope and drag sections, 44 and 46,respectively, are mounted within suitable frame members 60, andretainers 62 are provided between adjacent frame members to hold themold sections in an assembled relationship. When assembled, the mold 40is designed such that the ingate 48 thereof is in register with the bore64 of the pouring tube 30.

A groove 66 is formed near the outer periphery of each drag sectionsurface to retain a flange 68 depending from a contour insert member 70.One possible configuration of such a member is shown in FIG. 2, whichmay include a round outer surface 71 and an inner contoured surface 72of any desired shape, such as the sprocket contour shown. The insertmember 70 is preferably composed of cast iron to insure accuratecontours with repeated usage, but other chill materials, such asgraphite, may sometimes be employed.

As shown in FIG. l, an annular continuous dam or weir 74 is provided aspart of each drag section of the mold around the central passageway 52or ingate 48, as the case may be. The apex 7 6 of each weir 74 extendsupward for a height equal to or above the height of the casting cavity50, and each adjacent cope section is suitably contoured, such as at 78to accommodate the weir. Refractory cores 80 may be inserted betweenadjacent cope and drag sections, in order to impart apertures to thecasting. Suitable vent holes 82 communicating with the atmosphere at 84and 8S may be provided within the graphite mold sections 44, 46 and 54above and below and communicating with the refractory cores 80. Thecores 80 are preferably composed of a Zircon sand bonded by a resinmaterial or other suitable ceramic material and are designed to seat inthe lower vent hole.

lt should be noted that the ingate 48 is lined with a ceramic material`throughout substantially the entire length of the mold. This featureprevents freezing of the metal in the mold during the casting operationand allows the metal to drain freely from the ingate 48, as describedbelow.

guide plate 27 secured In operation, the ladle is filled with moltenmetal 36, placed in the tank 16, and the cover 18 is applied and sealedby actuation of the ram 26 ofthe ciamping device 22. Pressure is thenapplied to the tank 16 from pressure source 34, which causes the moltenmetal to rise upward through the bore 64 of the pouring tube 30 and filleach of the casting cavities 50. After the mold has been filled, thepressure in the tank 16 is relieved by opening a suitable valve 86connected thereto, thereby causing all excess metal in the passageway 52and the ingate 48 to be returned to the ladle 10. It may be seen thateach casting cavity 50 serves as a receptacle with the weir 74preventing return of metal in the cavity. Preferably, the mold isdesigned to retain sufficient metal in the casting cavity 50 in order toaccommodate volume contraction of the metal upon solidification. Whilesome metal may have to be removed by machining from the central portionof the casting, it may be seen substantially only that metal which isneeded to produce the final product is retained.

lclaim:

l. An apparatus for casting molten metal comprising a mold having anupper section and a lower section, said upper and lower sections matingwith one another and formed to define a casting cavity therebetween,ingate means in said mold for communication between said casting cavityand a source of molten metal, means for moving said molten metal intosaid ingate means to fill said casting cavity, drain means in a lowerportion of said mold for draining molten metal away from said castingcavity, wer means vertically surrounding said drain means for retainingmolten metal up to the intended height of the casting in said castingcavity upon the filling thereof, a plurality of bonded refractory coresbetween said upper and lower sections within said casting cavity, andvent means extending from said cores to the exterior of said mold.

2. An apparatus for casting molten metal comprising an upper section, alower section, a plurality of interchangeable mold sections engaged withone another and located between said upper section and said lowersection, said mold sections together with said upper section and saidlower section extending in a generally upward direction and definingtherebetween a plurality of annular casting cavities, a plurality ofrefractory cores in said casting cavities, vent means connecting certainof said cores to the exterior of said casting cavities, a commonupwardly extending passageway centrally located relative to said annularcasting cavities and in fluid communication. with each of' said castingcavities through an annular opening, an ingate located in said lowersection, said ingate being in fluid communication with said passageway,a plurality of annular continuous weirs around said central passageway,each of said weirs being located adjacent to one of said openings toeach of said casting cavities and having a circular apex extendingupwardly to a height above the uppermost portion of the respectivecasting cavity, means to force molten metal upwardly through said ingateinto said passageway over the circular apex of each of said weirs tofill each of said casting cavities, and means to remove said moltenmetal from said passageway whereby said weirs will retain molten metalin said casting cavities.

3. The apparatus set out in claim 2 wherein said means to force moltenmetal comprises a vessel filled with molten metal located below saidlower section, an upwardly extending tube communicating with said moltenmetal and said ingate means, means to exert pressure on said moltenmetal in said vessel to force molten metal upwardly through said tubeinto said ingate means and said passageway and wherein said means toremove said molten metal comprises means to reduce said pressure on saidmolten metal to allow said molten metal in said passageway and saidingate means to return to said tube.

4. The apparatus set out in claim 2 wherein certain of said cores arelocated along an upwardly extending line through said cavities, and saidvent means includes an upwardly extending tube between said cores alongsaid line, said tube being partially defined by a portion of said uppersection and by portions of said mold*sectiorls.

1. An apparatus for casting molten metal comprising a mold having anupper section and a lower section, said upper and lower sections matingwith one another and formed to define a casting cavity therebetween,ingate means in said mold for communication between said casting cavityand a source of molten metal, means for moving said molten metal intosaid ingate means to fill said casting cavity, drain means in a lowerportion of said mold for draining molten metal away from said castingcavity, weir means vertically surrounding said drain means for retainingmolten metal up to the intended height of the casting in said castingcavity upon the filling thereof, a plurality of bonded refractory coresbetween said upper and lower sections within said casting cavity, andvent means extending from said cores to the exterior of said mold.
 2. Anapparatus for casting molten metal comprising an upper section, a lowersection, a plurality of interchangeable mold sections engaged with oneanother and located between said upper section and said lower section,said mold sections together with said upper section and said lowersection extending in a generally upward direction and definingtherebetween a plurality of annular casting cavities, a plurality ofrefractory cores in said casting cavities, vent means connecting certainof said cores to the exterior of said casting cavities, a commonupwardly extending passageway centrally located relative to said annularcasting cavities and in fluid communication with each of said castingcavities through an annular opening, an ingate located in said lowersection, said ingate being in fluid communication with said passageway,a plurality of annular continuous weirs around said central passageway,each of said weirs being located adjacent to one of said openings toeach of said casting cavities and having a circular apex extendingupwardly to a height above the uppermost portion of the respectivecasting cavity, means to force molten metal upwardly through said ingateinto said passageway over the circular apex of each of said weirs tofill each of said casting cavities, and means to remove said moltenmetal from said passageway whereby said weirs will retain molten metalin said casting cavities.
 3. The apparatus set out in claim 2 whereinsaid means to force molten metal comprises a vessel filled with moltenmetal located below said lower section, an upwardly extending tubecommunicating with said molten metal and said ingate means, means toexert pressure on said molten metal in said vessel to force molten metalupwardly through said tube into said ingate means and said passagewayand wherein said means to remove said molten metal comprises means toreduce said pressure on said molten metal to allow said molten metal insaid passageway and said ingate means to return to said tube.
 4. Theapparatus set out in claim 2 wherein certain of said cores are locatedalong an upwardly extending line through said cavities, and said ventmeans includes an upwardly extending tube between said cores along saidline, said tube being partially defined by a portion of said uppersection and by portions of said mold sections.